1. Field
At least one embodiment of the present invention relates to testing alternating current or direct current power relays or switches.
2. Background
Electrically operated machines, such as general-purpose and special-purpose computing devices (e.g., “computers”), data storage systems, network servers, file servers, and Internet servers will fail or “crash” if not supplied with sufficient electrical power. As the purpose of such a machine becomes more important, so, too, are the measures taken to ensure that the machine's power source will not be interrupted. General-purpose and special-purpose computing devices commonly require direct current (DC) powered at several voltages. These DC voltages are typically produced by a system component called a power supply, which converts electrical energy from “hot” alternating current (AC) high voltage received, such as from a wall outlet, to DC lower voltages to be used by the device.
In order to protect a computing device, such as a network server, against power failures, a common technique is to install two or more identical power supplies, one or more of which is capable of providing the full amount of power required by the device. Also, the input of each power supply may be switched between one or more AC high voltage sources. For example, a first power supply may be connected to an ordinary wall socket or outlet which provides power at 120 Volts (V) AC at 60 Hertz (Hz) or 240 V AC at 50 Hz, while a second power supply is connected to an uninterruptable power supply (UPS) through another connection. If necessary, the UPS can provide power at a similar AC high voltage, such as from batteries. Thus, it is possible to use a relay or switch between the AC high voltage signals and the input of various power supplies of the computing device so that if either an AC high voltage power signal fails or a power supply fails, the computing device will continue to receive sufficient power to function.
In particular, a computing device, such as a network server may include switches or relays between “hot” alternating current high power input lines (e.g., such as connected to a wall socket and a UPS) and power supplies for supplying power to circuitry, components, mass storage device, disk drives, etc. of the computing device. A “hot” power signal may be defined as a signal within specification or within the contemplated specification for supplying power to a power supply of the computing device.
Often, to ensure functionality, computers and network servers include power transfer devices, switches, and/or relays to provide, prohibit, switch, or transfer power and/or ground to or between circuits and components. For instance, relays or switches may be used to switch the input or inputs of one or more computing device power supplies between two or more “hot” input AC high voltage signals, sources, generators, UPSs, etc. Thus, if an input AC high voltage signal, such as from a wall socket, UPS, or other source fails, relays or switches may be used to switch power supply input(s) to a different “hot” input AC high voltage signal. Similarly, if a power supply fails, relays or switches may be used to switch “hot” input AC high voltage signal(s) to a different functioning power supply. Thus, the relays and switches help ensure the reliability and functionality of the computing device by ensuring that it will continue to receive sufficient power to function. It can be appreciated that the reliability of the relays and switches will effect the reliability of the computing device. As such, it is desirable to ensure functionality of such relays and switches prior to needing them to switch power supply inputs to ensure the computing device does not fail. For instance, may be desirable to be able to determine when such relay or contact thereof is about to fail so that relay can be replaced or repaired prior to needing it to switch power supply inputs.